The invention relates generally to call processing in communication systems, and more particularly to systems in which calls or other communications are directed by a switch to or from wired or wireless telephones or other types of user terminals.
Conventional communication system switches, such as private branch exchanges (PBXs) and other premises-based telephone switches, generally support a wide variety of useful features, such as bridged call appearances, hunt groups, call forwarding, navigable directories, multi-call conferencing, etc. However, these and other switch-based features are typically provided only to those user terminals that represent internal extensions within the premises serviced by the switch. As a result, a user terminal associated with an external network is generally unable to avail itself of the full set of features supported by the switch.
By way of example, a mobile telephone or other mobile device representing a given external endpoint of the system generally cannot be treated as an internal extension of a conventional switch. A call directed from an internal extension of the switch to the given endpoint therefore must be processed as any other call to an endpoint of an external network, even if the given external endpoint is a device known to be associated with a user of an internal extension of the switch.
It is known in the art to implement call forwarding routines that will allow a call directed from one internal extension to another to be forwarded to a designated mobile telephone or other endpoint of an external network. However, in conventional call forwarding, the designated mobile telephone is not treated as if it were an internal extension serviced by the switch, and is generally unable to access many desirable features of the switch. Conventional switches are thus unable to extend switch-based features to such a call in an efficient and cost-effective manner.
A need therefore exists for call processing techniques that allow mobile telephones and other external system endpoints to access premises-based communication switch features in a manner similar to an internal extension serviced by the switch.
The present invention provides methods and apparatus for extending calls directed to internal switch extensions out to external networks, so as to allow a mobile telephone or other external endpoint to be treated as if it were an internal extension serviced by the switch.
In accordance with one aspect of the invention, a private branch exchange (PBX) or other communication system switch processes a call to determine if an identifier associated with the call has a corresponding entry in a stored list of external endpoints registered with the switch. The switch directs the call to an external port of the switch for delivery to a given one of the external endpoints if the identifier associated with the call has a corresponding entry in the stored list of external endpoints registered with the switch. The given external endpoint in an illustrative embodiment of the invention does not have a fixed external port assignment in the switch. Instead, the switch dynamically selects from a set of external ports an available external port over which the call is directed to the given external endpoint. The dynamic selection of the available external port may be implemented using an automatic route selection (ARS) algorithm.
In an illustrative embodiment of the invention, the switch directs the call to an external port of the switch via a loop-back arrangement implemented between port cards of the switch, e.g., a loop-back trunk between an output port associated with a first port card of the switch and an input port associated with a second port card of the switch. In other embodiments, the loop-back arrangement may be eliminated and the call routed directly to an external port of the switch after application of the ARS algorithm.
Advantageously, the invention allows a mobile telephone or other external endpoint to be treated as if it were an actual internal extension serviced by the switch. This in turn allows a given external endpoint to access at least a subset of the desirable call processing features provided by the switch, and thereby overcomes one or more of the above-described problems associated with conventional techniques.